There are numerous references that generally disclose beverage containers having a main or pour opening, and a separate vent opening formed on the same end panel as the main opening. The most common container, particularly for carbonated and malt beverages, is one that includes a tab to create the main opening from a scored area that surrounds a mouth portion of the end panel. The tab is typically secured by a rivet to the can end. The tab is lifted from one end, and a contact portion on the opposite end of the tab is lowered in contact with the end panel to impart a force on the mouth portion. The score is broken and the mouth portion is separated from the end panel by the force of the tab thus creating the main opening.
One example of a prior art reference disclosing a container end with a separate vent opening is the U.S. Pat. No. 5,011,037. This reference more particularly discloses a container end member having a first severable tab portion defined by a score line groove and an integral hinge for permanently securing the tab to the container. A force applying tab is mounted on the container end and is used to apply a force to the first severable tab portion to form the main or pour opening. A second severable tab portion is formed on the container end, also having an integral hinge portion for securing it to the container. The second severable tab portion has a raised surface projecting outwardly from the container end, so that a force may be more conveniently applied thereto to sever the second severable tab portion and form a vent opening in the container end.
Another example of a reference disclosing a container lid having a main opening and a separate vent opening includes the U.S. Pat. No. 5,819,973. This reference more specifically discloses a container lid having a vent tab for creating a pour opening, and also a vent hole for creating an air vent. A lift tab is pivotally mounted upon the lid. The lift tab has a handle end and an abutment end for exerting a downward force upon the panel covering the main opening. The opposite end of the handle when raised, exerts an upward force to open a vent hole rivet attached to the lift tab.